Tuberculin test variability: using the Norwegian Adrenaline-Pirquet method.

SETTING

Chest Unit, Bergen, Norway.

OBJECTIVES

To study the agreement between two Adrenaline-Pirquet tuberculin tests and compare reactivity in groups read after 2, 3 and 4 days.

DESIGN

Responders from a random sample of 1200 men and women 20-44 years of age in 1991 were tested with dual Adrenaline-Pirquet skin scratch tests with Norwegian-produced synthetic medium tuberculin and read after 2-7 days.

RESULTS

Of 588 subjects dually tuberculin tested, complete agreement existed in 220 (37.4%). A difference of 1 mm one way or the other was observed in 239 (40.6%), whereas a difference of less than 3 mm was found in 567 (96.5%). Using the larger of the two reactions increased the rate of tuberculin positivity (> or =4 mm) by up to 8.4% compared with reading only one of the tests. No statistically significant differences were observed between subjects whose reactions were read after 2, 3 and 4 days.

CONCLUSION

Under the non-blinded conditions of this study the dual Adrenaline-Pirquet tuberculin tests demonstrated reproducibility equivalent to the internationally recommended Mantoux test, and appeared to be independent of time of reading within four days.